An analytical method using high performance liquid chromatography (HPLC) with ultraviolet detection was developed for the measurement of bromocriptine, a dopaminergic agonist, in plasma and brain of rats. HPLC assays for chlorambucil and lipophilic derivatives were developed. Gas chromatographic/mass spectrometric assays for arecoline and scopolamine in rat plasma and brain and in human plasma were developed. The age-dependent pharmacokinetics of metachlorochlorophenylpiperazine, a serotonin autoreceptor agonist, were determined in rats.